System and method for predicting patient falls

ABSTRACT

A patient fall prediction system receives video image frames from a surveillance camera positioned in a patient&#39;s room and analyzes the video image frames for movement that may be a precursor to a patient fall. In set up phase, the viewpoint of the camera is directed at a risk area associated with patient falls, beds, chairs, wheelchairs, etc. A risk area is defined graphically in the viewport. The patient fall prediction system generates a plurality of concurrent motion detection zones that are situated proximate to the graphic markings of the risk areas. These motion detection zones are monitored for changes between video image frames that indicate a movement. The pattern of detections is recorded and compared to a fall movement detection signature. One fall movement detection signature is a sequential detection order from the motion detection zone closest to the risk area in the frames associated with patient falls, to the motion detection zone farthest away from the risk area. The patient fall prediction system continually monitors the motion detection zones for changes between image frames and compiles detections lists that are compared to known movement detection signatures, such as a fall movement detection signature. Once a match is identified, the patient fall prediction system issues a fall warning to a healthcare provider.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.10/735,307 filed Dec. 12, 2003, entitled Non-Intrusive Data TransmissionNetwork for Use in an Enterprise Facility and Method for Implementing,which is assigned to the assignee of the present invention. The aboveidentified application is incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to a patient monitor. Moreparticularly, the present invention relates to a system, method andsoftware program product for analyzing video frames of a patient anddetermining from motion within the frame if the patient is at risk of afall.

Fall reduction has become a major focus of all healthcare facilities,including those catering to permanent residents. Healthcare facilitiesinvest a huge amount of their resources in falls management programs andassessing the risk of falls in a particular patient class, location, andcare state, along with the risk factors associated with significantinjuries. Recent studies have found fall rates at 2.2 to 7.0 (per 1000patient bed days) in acute care hospitals, 11.0 to 24.9 in long-termcare hospitals, and 8.0 to 19.8 in rehabilitation hospitals, with themajority of falls occurring from, or near, the patient's bed, usually bypatients who should not ambulate without assistance. The patient'smental status is most often listed as the most common risk factorcontributing to falls. Bed falls can account for up to half of all fallsin a healthcare facility. The range of injury from all falls has beenreported to be at a rate of 29 to 48 percent, with 4 percent to 7.5percent resulting in serious injury to the patient. The intention ofthese studies is to improve patient care by providing adequatemonitoring programs corresponding to the perceived patient risk andinjury. Realistically, however, it is simply impossible to know for surewhich patient will fall, and the severity of the injury that may resultfrom any fall. Bed falls have received an extensive amount of scrutinydue to the patient's high expectation of safety and the disproportionalpotential for severe injury to the patient over other types of falls.

Round the clock patient monitoring by a staff nurse is expensive,therefore, healthcare facilities have investigated alternatives in orderto reduce the monitoring staff, while increasing patient safety. In thepast, patients at risk of falling from their beds were either physicallyrestrained or sedated, regardless of the patient's mental status. Bothof these preventives are now considered to be measures of last resortthat are reserved for unruly or incompetent patients. Presently, fallsprevention is subdivided into intervention and monitoring techniques.Interventions are aimed at minimizing falls risk and include suchmeasures as ensuring that the patient can reach necessary items from thebed, ensuring that the bed is in a low position and the bed brakes arelocked, ensuring that the patient has a manual bed call button withinreach for summoning a nurse and that a charge nurse responds (albeitverbally) to every call. Other interventions include the use of halflength bedrails to reduce the patient's need to climb over rails to exitthe bed and keeping the bedside area uncluttered and obstacle free.Perhaps the most easily implemented intervention is clear instructionsfrom an attending nurse to request assistance prior to leaving the bed.

Healthcare facilities rely on patient monitoring to supplementinterventions and reduce the instances of patient falls. Eyes-onmonitoring of patients is problematic for two reasons, cost and privacy.Most facilities maximize the patient-to-nurse staffing ratios by careunits, e.g., recovery and critical care units have a lowerpatient-to-nurse staffing ratio than floor bed units, and, typically,bed patients demand greater privacy than those in critical or specialcare units. For these reasons, patient monitoring has relied ontechnological solutions rather than nurse monitoring. Note however, thatthese solutions are alerting devices, used as an aid for patient careand are not a substitute for adequate quality staffing.

Prior art fall prevention monitors include alarms using pressuresensitive pads or position sensitive transmission patches. The firsttype of fall prevention monitor uses a pressure sensitive pad thatsenses the patient's body mass. If the sensor detects a change in thepatient's body mass, a remotely located alarm is sounded to summonstaff. These monitors are extremely adaptable and may be placed in oneor more locations on the patient's bed, on the floor adjacent to thebed, on chairs, toilet seats, wheel chairs and almost any other placethat a patient may rest. These devices have gained considerableacceptance in the healthcare industry because they are relativelyinexpensive, non-intrusive, exhibit a fairly low instance of falsealarms and are reliable. These monitors can be used in tandem to moreaccurately assess the position of a patient, thereby further reducingfalse alarms. For instance, the system may be configured with onepressure sensitive pad in the bed and under the patient and a secondpressure sensitive pad on the floor. Then, the staff will be alertedwhenever a patient's weights shifts off of the bed pad and again whenthe patient's weight is sensed by the floor pad.

Detractors to pressure sensitive fall prevention monitors counter thatthese types of devices may be more accurately described as “patient falldetectors” than “fall prevention monitors” because they typically alertonly after a fall has occurred and the patient's weight has shifted outof the bed. In other words, prior art pressure sensitive fall monitorscannot perceive that the patient is in the process of getting out ofbed, only that the patient's weight has left the bed. Additionally,poorly placed pressure sensitive pads may send multiple nuisance alarmsthat must be responded to and then to reposition the pressure sensitivepad requires that the bed be empty.

More recently, patient position sensitive transmission patches have beenintroduced that sense the position of a body part and send an alarm ifthe part is in a “near weight bearing position.” The “patch” is abattery powered inclinometer, processing circuitry and a transmitterenclosed in an adhesive patch that is used in conjunction with awireless receiver and alarm. The patch may be applied to the back of apatient's thigh parallel with the femur. Whenever the patient's thigh isapproaching a weight bearing angle, the patch sends an alert signal tothe remote receiver and an alarm sounds. These position sensitivetransmission patches are relatively inexpensive and can be worncontinuously for up to three weeks. The downside is battery life. Thetransmission patch device is essentially in a sleep mode when the patchis horizontal and consumes relatively little power, however when thepatch is oriented off horizontal, the inclinometer and associateelectronics are continuously processing measurements. Alerttransmissions consume even more battery power.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a system, method and softwareproduct for detecting motion and correlating that motion to movementsignatures that are precursors to a patient fall. The present patientfall prediction system may be implemented in a facility's existingsurveillance monitoring system. The system includes at least onesurveillance camera positioned in the patient's room for observing thepatient. Typically the healthcare professional is stationed remotelyfrom the patient room and monitors the system at the remote. In set upphase, the viewpoint of the camera is oriented toward an area in theroom associated with of elevated risk of patient falls, such as a bed,chair, wheelchair or shower. The patient will be located in this area.The healthcare professional observes the room setting on a monitor andidentifies an area in the viewport frame that will be monitored forpatient falls. This area is typically the origin of patient movement andthe general location of the patient in the viewport. Next, thehealthcare professionals defines specific areas on the display that areassociated with elevated risk for falling, usually by graphicallymarking these risk areas graphically on the screen. These high riskareas include the edges of a bed or chair, the side of a tub, a showerentry, or even an entryway threshold. Once identified by theprofessional, the patient fall prediction system monitors high riskareas for motion and correlates patterns of detected motion to knownmotion detection signatures. Some detection signatures represent generalmotion that does not correspond to patient falls, while others representpatient fall signatures, that is movement that is a precursor to apatient fall. When a detection pattern correlates to a fall detectionsignature, a fall alert is immediately transmitted to the healthcareprofessional at the remote location.

Motion patterns are detected through the use of concurrent detectionzones that are delineated adjacent to graphic markings of the risk areasmade by the healthcare professional. The purpose of the detections zonesis to predict patient falls based on the direction of motion detectedacross the detection zones. Detection patterns indicating an inwardmovement toward the patient are not precursors to falls and are usuallyignored. Conversely, motion detection patterns indicative of movementaway from the origin, outward from the patient, are indicative of a highrisk patient movements that may be a precursor to a fall. These outwardpatient movements are detected as sequential motion across the set ofdetection zones beginning with the innermost zone, then through theinternal detection zones of the set and finally are detected in theoutermost detection zone last (i.e., motion is detected chronologicallyfrom the innermost motion detection zone to the outermost zone). Oncematched to a fall detection signature, a fall alert is immediatelytransmitted to the healthcare professional.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The novel features believed characteristic of the present invention areset forth in the appended claims. The invention itself, however, as wellas a preferred mode of use, further objectives and advantages thereof,will be best understood by reference to the following detaileddescription of an illustrative embodiment when read in conjunction withthe accompanying drawings wherein:

FIG. 1 is a flowchart depicting a generic method for carrying outpatient fall predictions in accordance with an exemplary embodiment ofthe present invention;

FIG. 2 is a diagram of a patient fall prediction system in accordancewith exemplary embodiments of the present invention;

FIG. 3 is a diagram depicting the physical layout and logical topologyof a healthcare facility (HCF) as may utilize the present invention;

FIGS. 4A and 4B are video viewports 450 and 451 of identical patientrooms 420 as viewed by a healthcare provider on a display at computer212 in accordance with exemplary embodiments of the present invention;

FIG. 5 is a flowchart of a setup method implementing a patient fallprediction system for detecting patient movements that may be precursorsto a fall in accordance with an exemplary embodiment of the presentinvention;

FIGS. 6A-6D depict the bounding box method for defining a virtualbedrail in a display viewport in accordance with an exemplary embodimentof the present invention;

FIGS. 7A and 7B illustrate the line method for defining a virtualbedrail in a display viewport in accordance with another exemplaryembodiment of the present invention;

FIGS. 8A and 8B are diagrams of two possible configurations for motiondetection zones in accordance with exemplary embodiments of the presentinvention;

FIGS. 9A-9E graphically represent a response by the detection zones tothe type of specific patient movement that may be a precursor to a fallin accordance with one exemplary embodiment of the present invention;

FIG. 10 is a flowchart of a method for accumulating a detectionsignature using a detection list in accordance with one exemplaryembodiment of the present invention;

FIG. 11 is a flowchart of a method for clearing a detection list inaccordance with one exemplary embodiment of the present invention;

FIGS. 12A and 12B are diagrams that illustrate the distinctions betweena patient movement that is a precursor to a fall and a false alert inaccordance with one exemplary embodiment of the present invention; and

FIG. 13 is a flowchart of a method for discriminating a false alert froma fall alert in accordance with one exemplary embodiment of the presentinvention.

Other features of the present invention will be apparent from theaccompanying drawings and from the following detailed description.

Element Reference Number Designations  200: Patient monitoring system 201: Patient monitoring device  202: Video camera  204: Camera controldevice  205: Audible alarm  206: Processor  207: Receiver/interrigator 208: Memory (RAM and ROM)  209: Video processor  210: Nurse monitordevice  212: Computer (PC, laptop, net device)  214: Display(touch-screen)  216: User interface device (mouse)  220: Patient room 230: Care (Nurse) station  240: Distribution network  321: Bed  322:Wall  324: Night stand  326: Chair  327: Lavatory door  329: Entry door 341: Transmission medium  342: Network switch  343: Boradbandconnection  345: Patient administration  346: Networkserver/router/firewall  348: Network system administration  420: Patientroom  423: Ceiling  425: Floor  450: Image frame  451: Image frame  460:Orientation angle  461: Orientation angle  622L: Left imaginary fallrisk line  622R: Right imaginary fall risk line  630: Bounding screenobject  632: Screen pointer  650L: Left motion detection zones  650R:Right motion detection zones  722L: Left imaginary fall risk line  722R:Right imaginary fall risk line  742: Left line object  744: Right lineobject  750L: Left motion detection zones  750R: Right motion detectionzones  800: Viewport  802: Viewport  840: Virtual bedrail  850L: Leftmotion detection zones  850R: Right motion detection zones  860L: Leftmotion detection pixel line  860R: Right motion detection pixel line 912: Patient leg  951: Motion detection zone 1  952: Motion detectionzone 2  953: Motion detection zone 3  95n: Motion detection zone n 1212:Patient leg 1214: Patient arm 1251: Motion detection zone 1 1252: Motiondetection zone 2 1253: Motion detection zone 3  125n: Motion detectionzone n 1261: Column 1 1262: Column 2 1263: Column 3  126n: Column n

In the following description, reference is made to the accompanyingdrawings that form a part hereof, and in which is shown by way ofillustration, specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized. It is also to beunderstood that structural, procedural and system changes may be madewithout departing from the spirit and scope of the present invention.The following description is, therefore, not to be taken in a limitingsense. For clarity of exposition, like features shown in theaccompanying drawings are indicated with like reference numerals andsimilar features as shown in alternate embodiments in the drawings areindicated with similar reference numerals.

As will be appreciated by one of skill in the art, the present inventionmay be embodied as a method, system, or computer program product.Accordingly, the present invention may take the form of an entirelyhardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects all generally referred to hereinas a “circuit” or “module.” Furthermore, the present invention may takethe form of a computer program product on a computer-usable storagemedium having computer-usable program code embodied in the medium.

Any suitable computer readable medium may be utilized. Thecomputer-usable or computer-readable medium may be, for example but notlimited to, an electronic, magnetic, optical, electromagnetic, infrared,or semiconductor system, apparatus, device, or propagation medium. Morespecific examples (a nonexhaustive list) of the computer-readable mediumwould include the following: an electrical connection having one or morewires, a portable computer diskette, a hard disk, a random access memory(RAM), a read-only memory (ROM), an erasable programmable read-onlymemory (EPROM or Flash memory), an optical fiber, a portable compactdisc read-only memory (CD-ROM), an optical storage device, atransmission media such as those supporting the Internet or an intranet,or a magnetic storage device. Note that the computer-usable orcomputer-readable medium could even be paper or another suitable mediumupon which the program is printed, as the program can be electronicallycaptured, via, for instance, optical scanning of the paper or othermedium, then compiled, interpreted, or otherwise processed in a suitablemanner, if necessary, and then stored in a computer memory. In thecontext of this document, a computer-usable or computer-readable mediummay be any medium that can contain, store, communicate, propagate, ortransport the program for use by or in connection with the instructionexecution system, apparatus, or device. The computer-usable medium mayinclude a propagated data signal with the computer-usable program codeembodied therewith, either in baseband or as part of a carrier wave. Thecomputer usable program code may be transmitted using any appropriatemedium, including but not limited to the Internet, wireline, opticalfiber cable, RF, etc.

Moreover, the computer readable medium may include a carrier wave or acarrier signal as may be transmitted by a computer server includinginternets, extranets, intranets, world wide web, ftp location or otherservice that may broadcast, unicast or otherwise communicate anembodiment of the present invention. The various embodiments of thepresent invention may be stored together or distributed, eitherspatially or temporally across one or more devices.

Computer program code for carrying out operations of the presentinvention may be written in an object oriented programming language suchas Java7, Smalltalk or C++. However, the computer program code forcarrying out operations of the present invention may also be written inconventional procedural programming languages, such as the “C”programming language. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer. In the latter scenario, theremote computer may be connected to the user's computer through a localarea network (LAN) or a wide area network (WAN), or the connection maybe made to an external computer (for example, through the Internet usingan Internet Service Provider).

A data processing system suitable for storing and/or executing programcode may include at least one processor coupled directly or indirectlyto memory elements through a system bus. The memory elements can includelocal memory employed during actual execution of the program code, bulkstorage, and cache memories which provide temporary storage of at leastsome program code in order to reduce the number of times code must beretrieved from bulk storage during execution.

Input/output or I/O devices (including but not limited to keyboards,displays, pointing devices, etc.) can be coupled to the system eitherdirectly or through intervening I/O controllers.

Network adapters may also be coupled to the system to enable the dataprocessing system to become coupled to other data processing systems orremote printers or storage devices through intervening private or publicnetworks. Modems, cable modem and Ethernet cards are just a few of thecurrently available types of network adapters.

The present invention generally relates to a patient monitoring usingcaptured video image frames of the patient for detecting circumstancesin which the patient is at an elevated risk of falling. Video monitoringof patient activity is known, such as described in U.S. patentapplication Ser. No. 10/735,307 filed Dec. 12, 2003 by Johnson andentitled Non-Intrusive Data Transmission Network for Use in anEnterprise Facility and Method for Implementing. The aforementionedJohnson application also describes detecting patient movements byanalyzing sequential frames of video images for changes. A video monitorcamera system is installed in the patient's room and aimed at an area ofinterest in the room, such as at the patient. Sequential image framesare compared for differences that indicate movement. Once detected, thesystem flags the sequence of images for local storage that can beremotely retrieved at a later time. Furthermore, the Johnson applicationdescribes techniques for filtering out unimportant motion in the frameand concentrating on only relevant areas of the image, such as thepatient's bed, the area proximate to the patients bed or any other areain the patient's room, thereby saving only the video sequences that arerelevant. While these stored video sequences are an important supplementto medical records, the patient monitoring system stores all sequencesin which motion is detected without regard to the patient's risk offalling.

One area of particular concern for healthcare facilities is patientfalls, particularly from the patient's bed. Typically, a healthcarefacility is subdivided into corridors of patient rooms with a centrallylocated care station (the nurse's station) responsible for a group ofrooms. The care station is usually connected to each patient room by atleast an intercom system. Each room has a call device that triggers anaudible alert at the care station, usually coupled with visual roomidentification indicia at the care station. Normally, at least onehealthcare professional remains in the care station to monitor thepatient call system while others go about their routines in and out ofpatient rooms and other areas of the facility. Patients who should notambulate without assistance are instructed to call for assistance asthey are prone to bed falls, although virtually every patient is at somerisk of a bed fall. Patients do not, or sometimes cannot, followinstructions which results in falls and possible injuries. Motiondetectors, while helpful in detecting patient movements that mightresult in a fall, tend to generate a disproportionately high percentageof false alarms. Responding to multiple false alarms tends todesensitize healthcare professionals to the perceived risk of a patientfall. Pressure sensitive pad patient monitors are at the other extreme,that is, they tend to alert only after the patient is in an unsteadystate and in the process of falling, such as when the patient's weightshifts from the bed during egress. Once in an unsteady state, it isdifficult for a healthcare professional to respond before the patientfalls. Patient position sensitive transmission patches alert theprofessional whenever the part of the patient's body having the padrotates at a particular angle indicating that the patient is attemptingto move into a more vertical position. These systems cannot detectcertain critical patient movements that precede a fall, such as apatient rolling off a bed in a generally horizontal attitude or fallingbackwards from a sitting position off the bed. Furthermore, the lattertwo devices generally require installing of standalone fall detectionequipment.

Recently, the U.S. Congress adopted Public Law No: 110-202 entitled“Keeping Seniors Safe From Falls Act of 2007” for identification,analysis, intervention and rehabilitation of persons at risk of falling.This law may mandate minimal standards for patient fall care andmonitoring. What is needed is a patient fall prediction system thatdetects patient activity in situations indicative of a probable fall andgenerates an alert prior to the fall event, thereby allowing thehealthcare professionals sufficient time to react before the actualfall. Optimally, the system could be incorporated in technology existingin the healthcare facility and should be adaptable for monitoring forpatient falls under a variety of conditions.

The present invention is directed to a patient fall prediction systemthat may be implemented in a facility's existing surveillance monitoringsystem. FIG. 1 is a flowchart depicting a generic method for carryingout patient fall predictions in accordance with an exemplary embodimentof the present invention. The process begins by determining an area inthe viewport frame that will be monitored for patient falls. This areais the origin of patient movement, hence is usually the general locationof the patient in the viewport (step 102). Next, the areas around thepatient that may be associated with elevated risk for falling areidentified in the viewport (step 104). Typically, these areas includehazards such as the edge of a bed or chair, the side of a tub, a showerentry, or even an entryway threshold. Once these areas have been definedin the viewport, the patient fall prediction system monitors them formotion (step 106). One advantage of the present invention is that itdoes more than merely monitor areas proximate to a patient that may havesome inherent risk of falling, instead the fall prediction methodologyactually analyses motion with those areas for a specific type of motionthat may be a precursor to a patient fall (step 108). Any motionsdetected in the monitored area that are not precursors to a fall aredisregarded. However, even though the system identifies a specific typeof motion that always precedes a fall, not all of these motions willresult in a patient fall, some are false alarms, which are disregarded(step 110). Only specific motion detected within the monitored area thatis a precursor to a fall and is not a false alarm will trigger an actualalarm (step 112).

Briefly, a video camera is securely positioned at a vantage point withan unobstructed view of the patient's area, typically the patient's bed.A healthcare professional views the patient room setting on a monitor,usually remote from the patient, and manually draws a bounding area, orother graphic object, on the screen that defines an area of high riskfor patient falls, for instance around a patient's bed. This object issometimes referred to as a virtual bedrail. The origin of any motionthat could be a precursor to a patient fall is located within thatobject. Once defined, the patient fall prediction system delineates aset of concurrent motion detection zones, in the video viewport, thatare adjacent to the risk area. As such, these detection zones arepositioned on each risk side of the perimeter of the virtual bedrail.Each set of detection zones comprise several concurrent detections zonesthat should not overlap. In operation, the fall prediction systemmonitors each set of motion detection zones for a specific type ofmotion originating at the origin that would indicate that a patient isat an elevated risk of falling. The system sounds a fall alert at thecare station prior to the patient entering a state in which a fall isimminent. General patient movements that are not precursors to a fallare disregarded, as is any other general motion detected in the imagenot related to the patient. These movements are either: not within themonitored zones; do not originate at the origin; do not traverse thedetections zones; or are some combination of the above. Detecting thespecific type of motion that is a precursor to a fall is accomplished byanalyzing the direction of motion across a set of detection zones.Motion traversing the virtual bedrail from the outside could not be fromthe patient (or at least is not a precursor movement to a fall) and,therefore, are not predictive of a patient fall. Conversely, specificmovements traversing the detection zones from the origin must be aresult of a patient movement and a patient fall is always proceeded bysuch movements. Furthermore, the degree of movement, its position alongthe virtual bedrail and duration may be scrutinized for more definitiveclues suggesting a fall. The present patient fall prediction system mayalso be combined with a deactivator for temporarily deactivating thefall alert under certain conditions, such as when a healthcareprofessional is in the patient's room. A more complete understanding ofthe exemplary embodiments of the present invention is best understood byreference to a description of the accompanying figures.

Before discussing the present invention in detail, it should beappreciated that the physical structure of the device may take manyforms and operate in a variety of modes without departing from theintended scope of the invention. A brief description of severalstructural exemplary embodiments is discussed immediately below. FIG. 2is a diagram of a patient fall prediction system in accordance withexemplary embodiments of the present invention. As depicted in thefigure, patient fall prediction system 200 generally comprises patientmonitoring device 201 and nurse monitor device 210. Patient monitoringdevice 201 captures video images of a portion of the patient's room 220via camera 202, which is coupled to camera control device 204. Camera202 should be at least of medium quality, produce a stable video outputof 300 lines of resolution or greater and have infrared illumination orquasi night vision for operating in extremely low light conditions.Additionally, video camera 202 should have a relatively fast shutterspeed to capture relatively fast movements without blurring at framerates of 20 fps or above. Camera control device 204 processes the videoimages received from camera 202 in accordance with the novel fallprediction methodology discussed below. As such, camera control device204 includes processor 206, memory 208 and optional video processor 209.Camera control device 204 may be a special purpose device configuredspecifically for patient monitoring, such as the set-top control andcamera control devices described in the Johnson application identifiedabove or, optionally, may be a generic personal computer (PC). In eithercase, memory 208 includes both ROM and RAM type as necessary for storingand executing fall prediction program instructions and a high capacitymemory, such as a hard drive for storing large sequences of video imageframes. Additionally, camera control device 204 may be fitted with ahigh capacity flash memory for temporarily storing temporal image framesduring image processing and/or prior to more permanent storage on a harddrive or at a network location. Optional video processor 209 may be adedicated image processor under the control of an application routineexecuting on processor 206, or may be logic operating in processor 206.Under the fall prediction routines, video processor 209 analyzesportions of sequential images for changes in a particular area whichcorrelate to patient movements that are precursors to a fall. Patientmonitoring device 201 may be coupled to nurse monitor device 210 locatedin nurses station 230 via distribution network 240, for transmittingsurveillance images of the patient's room and fall state information tonurse monitor device 210. Optionally, audible alarm 205 may be providedfor alerting healthcare professionals that camera control device 204 hasdetected that the patient is at risk of falling. Additionally, cameracontrol device 204 comprises other components as necessary, such asnetwork controllers, a display device and display controllers, userinterface, etc.

In many regards, nurse monitor device 210 may be structurally similar tocamera control device 204, however its primary functions are to set upthe fall prediction routines running at camera control device 204 and tomonitor fall state information and surveillance video provided bypatient monitoring device 201. Optimally, nurse monitor device 210 isconnected to a plurality of patient monitoring devices that are locatedin each of the patient rooms being monitored at the nurse station. Nursemonitor device 210 generally comprises computer 212 coupled to display214. Computer 212 may be a personal computer, laptop, net computer, orother net appliance capable of processing the information stream.Computer 212 further comprises processor 206, memory 208 and optionalvideo processor 209, as in camera control device 204, however thesecomponents function quite differently. In setup phase, a healthcareprofessional views the patient room setting and graphically definesareas of high risk for a patient fall, such as the patient bed, chair,shower, tub, toilet or doorways. The graphic object may be manipulatedon display 214 by user gestures using resident touch screen capabilitiesor the user gestures may be entered onto a display space using mouse 216or other type user interface through a screen pointer (not shown). Thatinformation is passed on to patient monitoring device 201 which monitorsthe selected area for motion predictive of a movement that is aprecursor to a patient fall. When patient monitoring device 201 detectsthat the patient is at high risk of falling, the fall state isimmediately transmitted to nurse monitor device 210, which prioritizesthe information over any other routine currently running as an alarm.This is accompanied by an audible alarm signal (via audible alarm 205).The healthcare provider can then take immediate response action toprevent a patient fall.

In accordance with other exemplary embodiments of the present invention,patient monitoring device 201 may operate independently, as aself-contained, standalone device. In that case, patient monitoringdevice 201 should be configured with a display screen and user interfacefor performing setup tasks. Audible alarm 205 would not be optional. Inaccordance with still another exemplary embodiment, patient monitoringdevice 201 may comprise only video camera 202, which is coupled to nursemonitor device 210 at a remote location. In operation, camera 202transmits a stream of images to nurse monitor device 210 for videoprocessing for fall prediction. It should be appreciated, however, thatoften high volume traffic on distribution networks, such as sequences ofvideo images, experience lag time between image capture and receipt ofthe images at the remote location. To avoid undesirable consequencesassociated with lag, the distribution network bandwidth should besufficiently wide such that no lag time occurs, or a dedicated videopath be created between nurse monitor device 210 and patient monitoringdevice 201. Often, neither option is practical and therefore, the videoprocessing functionality is located proximate to video camera 202 inorder to abate any undesirable lag time associated with transmitting theimages to a remote location.

In addition, patient fall prediction system 200 may comprise adeactivator for temporarily disabling the patient fall prediction systemunder certain conditions. In the course of patient care, healthcareprofessionals move in and out of patient rooms and in so doing, solicitmovements from the patients that might be interpreted as a movement thatproceeds a patient fall by the patient fall prediction system.Consequently, many false alarms may be generated by the mere presence ofa healthcare professional in the room. One means for reducing the numberof false alarms is to temporarily disarm the patient fall predictionsystem whenever a healthcare professional is in the room with a patient.Optimally, this is achieved through a passive detection subsystem thatdetects the presence of a healthcare professional in the room, using,for example, RFID or FOB technology. To that end, patient monitoringdevice 201 will include receiver/interrogator 207 for sensing an RFIDtag or FOB transmitter. Once patient monitoring device 201 recognizes ahealthcare professional is in the proximity, the patient fall predictionsystem is temporarily disarmed. The patient fall prediction system willautomatically rearm after the healthcare professional has left the roomor after a predetermined time period has elapsed. Alternatively, thepatient fall prediction system may be disarmed using a manual interface,such as an IR remote (either carried by the healthcare professional orat the patient's bedside) or a dedicate deactivation button, such as atcamera control device 204 or in a common location in each of the rooms.In addition to the local disarming mechanisms, the patient fallprediction system may be temporarily disarmed by a healthcareprofessional at care station 230 using computer 212 prior to enteringthe patient's room

FIG. 3 is a diagram depicting the physical layout and logical topologyof a healthcare facility (HCF) as may utilize the present invention. TheHCF is typically configured with a plurality of patient rooms 220 andone or more care station 230 statistically located for servicing apredetermined number of rooms in the vicinity. Patient rooms 220 areusually identical in size, design and layout with similar furnishings.An exemplary room will have egress door 329, lavatory door 327 and walls322 (see FIGS. 4A and 4B discussed below). Furnishings typically includebed 321, night stand 324 and usually one or more chairs 326. Inaccordance with exemplary embodiments of the present invention, patientroom 220 will also include patient monitoring device 201 for monitoringpatient movements. Each patient monitoring device 201 is connected todistribution network 240 for sending and receiving programminginstructions, video frames, patient fall state information and othertypes of media and data. As depicted in the figure, distribution network240 is pervasive across the HCF including patient rooms 220, carestation 230, administration sites 345 and network system administrations348. Distribution network 240 includes a plurality of data pathscomprising any type of medium for data transmission. For instance, datatransmission medium 341 may be a wired network, e.g., twisted conductorpairs of conductor, coaxial, optical or wireless signals, each usingappropriate data transmission equipment and transmission protocols fortransmitting data and video images. Distribution network 240 alsocomprises network switches 342, firewall/servers 346 and computers 212which may be personal computers, laptops, net computers, or other netappliances capable of processing the information stream, and may beconnected to the Internet via high speed line 343. In accordance withone exemplary embodiment of the present invention, computers 212 will beoptionally coupled to touch-screen display capable of receiving andechoing user gestures in display space (see nurse monitor device 210).

Before discussing the present invention in greater detail, it will behelpful to view a typical patient room from a viewpoint perspective of avideo image. FIGS. 4A and 4B are video viewports 450 and 451 ofidentical patient rooms 420 as viewed by a healthcare provider on adisplay at computer 212. Within each room can be seen side walls 322,ceiling 423 and floor 425. Along one wall 322 is entry door 329 andbathroom door 327. Each room has identical furnishings: bed 321, nightstand 324 and chairs 326. Although the rooms are nearly identical,careful scrutiny of viewports 450 and 451 frames will reveal that theview angle of the cameras in each room are different. More importantly,the orientation angle 460 of bed 321 to the camera in frame 450 haschanged in frame 451 to a different orientation, angle 461. Clearly, anypatient monitoring system should have the flexibility to adapt to alldifferent room configurations in the HCF.

In operation, patient fall prediction system 200 operates in two modes:setup; patient monitoring. FIG. 5 is a flowchart of a setup methodimplementing a patient fall prediction system for detecting patientmovements that may be precursors to a fall in accordance with anexemplary embodiment of the present invention. The setup procedure isinvoked at, for instance, nurse monitor device 210 where a healthcareprofessional defines a virtual bedrail in display space (step 502).Alternatively, the virtual bedrail may be input using patient monitoringdevice 201 at the patient's room, as mentioned above. The virtualbedrail defines an area of fall risk for the patient, such as the edgeof a bed or chair, or even the toilet, shower or tub. Exemplarymechanisms for defining a virtual bedrail will be discussed with regardto FIGS. 6A through 6D, 7A and 7B. Typically, a virtual bedrail objectis displayed in an overlapping position on the image frame at nursemonitor device 210. Next, the nurse monitor device 210 translates thatobject to input space (step 504). The present method for detectingpatient movements may be implemented in any space, i.e., the input spaceassociated with the camera's image sensor (sometime referred to as a rawimage), the display space associated with the display device (sometimereferred to as a raster image) or some other intermediate space.However, operating in input space may be marginally faster becausepatient monitoring device 201 need not translate the generallyrectangular grid of input pixels into a second rectangular grid ofraster pixels. More importantly, by making calculation in input space,no additional error introduced from translating the pixels that mightreduce the accuracy of the motion detection process. Furthermore, and asmentioned above, it is expected that patient monitoring device 201 willbe primarily responsible for motion detection image processing, whichoperates in input space. Hence, the user defined virtual bedrail objectis passed from nurse monitor device 210 to patient monitoring device201.

Once the virtual bedrail object has been accepted by patient fallprediction system 200, the interior of the virtual bedrail is determined(step 506). It should be appreciated that, since present patient fallprediction system 200 assesses fall risk based on the direction ofmovement detected between images, the absolute direction of the motionvaries with the location of the movement within the image. An origin ofthe movement is determined from the location of the virtual bedrail onthe image. Only motion detected between viewports that signifiesmovement in a direction away from the origin is of interest. If thatmovement completely traverses the virtual bedrail, it is recognized bypatient fall prediction system 200 as a fall risk movement. With therisk directions determined, the patient fall prediction system createsmultiple adjacent motion detection zones adjacent the virtual bedrail(step 508). Typically, the motion detection zones are positioned on theexterior of the virtual bedrail, but may overlap it. The creation of themotion detection zones and their operation will be discussed below,briefly however, risk is assessed across a sequence of images in whichmovement is detected move through the plurality of detection zones. Forinstance, a movement signature that is detected in the outermostdetection zone, then sequentially in the internal zone(s) and lastly inthe innermost zone is consistent with an inward motion that is usuallyinitiated by something other than the patient (i.e., a patient's motionis detected in chronological order from the innermost motion detectionzone to the outermost zone). The type of motion does not represent aheightened fall risk state for the patient. Conversely, a movementsignature that is detected in the innermost detection zone and thenthrough the internal detection zone(s) and lastly in the outermost zoneis consistent with an outward movement of the patient. Every patient bedfall is proceeded by an outward movement signature that traverses a setof detection zones (although not every outward movement signature isfollowed by a bed fall). Finally, with the sets of detection zones inplace, patient fall prediction system 200 proceeds to monitoring mode(step 510).

FIGS. 6A-6D, 7A and 7B are diagrams depicting the creation of a virtualbedrail on a display in the setup mode in accordance with exemplaryembodiments of the present invention. FIGS. 6A-6D depict the boundingbox method and FIGS. 7A and 7B illustrate the line method. Regardless ofwhich method is used, the aim is merely to define the boundary ofelevated risk for patient falls. It is expected that in almost everycase the patient's bed will not lie square with the display screen, butwill be oriented at some angle to it. The bounding box must bemanipulated into a corresponding orientation to the bed. With regard toFIGS. 6A-6D, bed 321 is displayed in which two imaginary lines thatrepresent patient fall risk can be envisioned, risk line 622L and riskline 622R. Imaginary risk lines 622L and 622R are represented in thefigure merely to emphasize a boundary elevated risk for patient falls,such as the edge of a bed or chair, the side of a tub or shower, or evena doorway or threshold. Imaginary risk lines 622L and 622R are notdisplayed in image frame to the healthcare professional. The intentionis to create a visual bounding box object collinear with the risk lines,wherein motion detection zones will be aligned. Initially, object 630 isopened on the screen, such as by manipulating screen pointer 632 usingmouse 216 or other type of user interface device. Object 630 may beinvoked on display screen 214 as a drawing object by using anuncomplicated drawing routine. The drawing object must be recognized asa virtual bedrail by patient fall prediction system 200. Alternatively,object 630 may be created by a touch gesture directed across touchscreen 214. In FIG. 6A, bounding box object 630 is expanded across thehorizontal extent of bed 321 at the headboard. This is typically done bygrabbing a side of box object 630 with screen pointer 632. Next, in FIG.6B bounding box object 630 is expanded across the vertical extent of bed321 to the footboard. The lower side of box object 630 is thenmanipulated across the lower portion of bed 321, thereby transformingthe rectangle into a rhomboid shape as depicted in FIG. 6C. Notice thatthe left and right sides are now approximately collinear with risk lines622L and 622R and the bounding box virtual bedrail is complete. The usercan make minor adjustments to box object 630 as necessary. Finally, atleast two sets of detection zones are delineated from the lateral sidesof box object 630 outward, detection zones 650L and detection zones650R. The detection zones are automatically created by the patient fallprediction system with box object 630. Optionally, patient fallprediction system 200 may require the user to identify the interior ofthe object (the origin of movement), by pointing to it, in order tocreate detection zones 622L and 622R and determine the risk directions.As depicted in the figure, detection zones 622L and 622R are createdwith respect to the lateral sides of bed 321 and adjacent to imaginaryrisk lines 622L and 622R. In addition, upper and lower sets of detectionzones may be simultaneously created that are adjacent to the upper andlower sides of box object 630. Since these areas have a relatively lowfall risk, the upper and lower sets of detection zones are optional.

The drawing operation for creating line objects 742 and 744 depicting inFIGS. 7A and-7B is similar to that described above in FIGS. 6A-6D,however line objects 742 and 744 are directly drawn at imaginary risklines 722L and 722R. The patient fall prediction system detectiondelineates the two separate sets of detection zones; detection zones750L for line object 742 and detection zones 750R for line object 744.It should be appreciated that although in the description of presentexemplary embodiment, the virtual bedrail is manually defined on thedisplay area, the present fall prediction system may automaticallyrecognize areas of elevated risk in the image frame and define anappropriate virtual bedrail without human intervention. In that case,the healthcare professional need only confirm the placement of thevirtual bedrail and/or modify its size and location as necessary.

It should be mentioned that even though the present invention isdescribed using essentially linear risk lines, these lines may be anvirtually shape to accommodate any risk area without departing from thescope of the present invention. For instance, either or both ofimaginary risk lines 722 l and 722R may be curvilinear in order toconform to a curved risk surface. Alternatively, the imaginary risk linemay form a closed geometric shape, such as a circle or some irregularlygeometry. In either case, line objects are drawn in the viewportcoextensive with the risk lines associated with the risk area, fromwhich a plurality of detection zones are delineated. The detectionszones will then follow the contour of the line drawn object(s) asdiscussed immediately above.

Detecting motion in the detection zones can be accomplished using asuitable means in monitor mode, for instance, video from video camera202 is converted to 24 bit RGB frames (red, green and blue values perpixel), at a flexible rate of fps (frames per second) depending on theprecision needed, which, for this application, is primarily determinedby the distance between video camera 202 and the bed, i.e., the size ofthe bed/patient in the viewport. Motion detection commences after twoframes are buffered, at which time the sets of detection zones, asdefined by a viewport of the video, are monitored. A change value iscalculated for each detection zone in its viewport. These change valuesare then compared against an average idle change delta (IDLE_Δ, themean), and an idle range (IDLE_RANGE, the median). If the change valuefalls outs a range of the IDLE_Δ+/− the IDLE_RANGE, than motion isdetected in that detection zone.

More particularly, motion detection is accomplished by taking twosubsequent RGB frames and subtracting the RGB values of the new framefrom the previous frame for each pixel within the viewport of eachmotion detection zone, then converting that value to an absolute value(negatives become positives). These values are summed, and then dividedby the total number of pixels in the detection zone. The result is adouble precision value from 0-1 representing the average pixel changefor the detection zone. This value is called the detections zone'sMOTION_Δ. The MOTION_Δ's are compared to an IDLE_Δ and idle range whichis the representation of the typical average change in pixels when nomotion occurs. The IDLE_Δ is a side effect of digital compression ofvisual data. Whenever a detection zone's MOTION_Δ goes outside theIDLE_Δ+/−IDLE_RANGE, that detection zone is flagged as an active zonebeing in motion. A detection zone remains “in motion” until the MOTION_Δreturns to within the IDLE_Δ+/−IDLE_RANGE, for a given amount of time,giving it the state of “in motion” a decay effect.

Using the detection methodology has the advantage of being able toreadily detect motion regardless of the ambient RGB values from thedetection area, because only a change in the relative values isconsidered. Hence, acceptable values for IDLE_Δ and IDLE_RANGE may bedetermined in advanced and preset in the system. Alternatively, thevalues for IDLE_Δ and IDLE_RANGE may be used as defaults, which areupdated by the system over time. For instance, under high lightconditions, with less color noise, the tolerances for IDLE_Δ andIDLE_RANGE may be relatively low without the possibility of missing amotion event or generating false detections. On the other hand, inconditions where the color noise is higher, such as low lightconditions, the tolerances for IDLE_Δ and IDLE_RANGE may be relativelyhigh. For that case, the values for IDLE_Δ and IDLE_RANGE may besomewhat higher to avoid triggering false detections from noise.Consequently, the values for IDLE_Δ and IDLE_RANGE may adaptivelyupdated by the system based on temporal factors, such as lightingconditions, the ambient color and/or luminosity.

Alternatively, motion detection may also be accomplished by downsampling the frames into grayscale images first, then comparing thedifference by subtraction, as described above. This method require lessprocessing power, as only one value is calculated, the luminance,however is also less accurate because it is more prone to missing achange of color and intensity as there are fewer representations ofcolor in grayscale than there are combinations of different colors andintensities.

Image compression may also be used for a motion determination mechanism.The separate detection zones are compressed independently in one frameand then compressed again with the same algorithm in the next frame. Thedifference in sizes of the compressed zones is an indication of motion.

The purpose of creating sets of n detections zones is to aid indistinguishing general movement from a specific movement that isindicative of a high risk movement that precedes a fall. The motionsignature of high risk movement is always in an away from the origin orin an outward direction from the virtual bedrail. Hence, the movementsignature of the specific motion of interest will proceed from the innerdetection zones to the outer detection zone sequentially. However, thegeometry of the motion detection zones may vary and be adapted for theparticular system employed and for the camera viewpoint. Essentially,the detection zones are groups of pixels from the viewport to beprocessed by video processor 209. Certain types of pixel configurationsare less computationally intensive than others, thereby allowing for amore immediate result. It should be remembered, however, that theviewport is a two-dimensional representation of a three-dimensional areabeing monitored. Therefore, certain general movements inthree-dimensional space of the patient's room can be interpreted as thespecific type of movement preceding a fall and trigger a false alarm.Some of these false alarms can be mitigated by narrowing the field ofview of the camera and through the placement of the camera, i.e.,elevating the position of camera 202 so that pedestrian traffic does notintersect the view path to the detection zones. Others can becircumvented by the configuration of the detection zones.

FIGS. 8A and 8B are diagrams of two possible configurations for motiondetection zones in accordance with exemplary embodiments of the presentinvention. In viewport 800 in FIG. 8A, sets of detection zones 850L and850R are adjacent to the outward edge of virtual bedrail 840 andcomprise zone 1 through n. form the innermost zone to outermost. Thereshould be at least two concurrent zones (i.e., n>1), however thepractical upper limit is constrained by processing capacity and thephysical dimension of the projection of the zones in the viewport. Inother words, the width of detection zones 850, w₁, should be smallenough that the patient would traverse all n zones before a fall isimminent, between two and six inches (i.e., 6 in>w₁>2 in). One means toensure that w₁ is not too large is by relating it to a known dimension,which is problematic since the viewport is dimensionless. Nevertheless,the dimensions of common objects in a healthcare facility are known. Forinstance, a standard hospital bed is approximately 55 inches wide andsince virtual bedrail 840 is drawn with that width, it can be assumedthat the width of virtual bedrail 840, w₂ is approximately 55 inches.Therefore, the width of detection zones 850, w₁, can be referenced tothe virtual bedrail, i.e., (55/6×w₂)>w₁>(55/2×w₂), which can becalculated automatically by patient fall prediction system 200. If fourzones are desired (i.e., n=4), each zone has a width of 0.25w₁regardless of how may columns of pixels are contained in each zone.

Alternatively, it may be desired to define each of zones 1-n as havingonly a single pixel column as depicted in viewport 802 of FIG. 8B.There, n may be significantly larger than four. This configuration isparticularly expedient in situations where the sides of bed 321correlate with columns of pixels in the viewport, i.e., the bed isapproximately aligned with the viewport. Then, a motion detection zoneis delineated as an entire column of pixels in viewport 802, e.g., setsof zones 860L and 860R. Although defining the detection zones as singlecolumns of pixels may be computationally more expedient, the overlapfrom virtual bedrail 840 will result in false alarms. Therefore, fordetection zones comprising column of pixels, such as is viewport 802,optimally the camera should be posited at an elevated viewpoint and thefield of view constrained to bed 321.

As mentioned above, the motion detection zones are employed as amechanism for distinguishing a specific type of motion that may be aprecursor to a patient fall from more general motion. In accordance withone exemplary embodiment of the present invention, the fall predictionsystem compares each set of motion detection zones with thecorresponding zones from the previous imaged frame for changes andretains the detection order in a separate detection list for each set ofzones. The detection list is a list of the detection zones which haveexperienced changes between the most recent image frames, and in theorder that the detections were noticed. The detection list iscontinually updated with additions and deletions based on new detectionsand abatements and the detection list is compared to known detectionsignatures. The detection signature of the specific motion preceding afall is always from the innermost detection zone, traversing all of theinterior zones, to the outermost zone. FIGS. 9A-9E graphically representa response by the detection zones to the type of specific patientmovement that may be a precursor to a fall in accordance with oneexemplary embodiment of the present invention. In FIG. 9A-9E the patientis resting in bed 321 with her legs 912 is a recumbent position. Zones951, 952, 953 through 95 n represent zones 1, 2, 3 and n, respectively.As the patient moves from the origin outwardly, motion is detected firstin zone 951, represented as shaded (FIG. 9B), then zone 952 (FIG. 9C)and followed by zone 953 (FIG. 9D). Finally, motion is detected in zone95 n (FIG. 9E), resulting in the issuance of a fall alarm. Consequently,and in accordance with one exemplary embodiment of the presentinvention, the detection signature of interest is: zone 1, zone 2, . . ., zone (n−1), zone n. Movement of healthcare professionals and visitorsinteracting with the patient will never originate at the origin and,therefore, produce a different detection signature, one of generalmovement, i.e., zone n, zone (n−1), . . . , zone 2, zone 1. It should beappreciated that although the detection signatures are derived insequential image frames, the frames are not necessarily consecutive.Assuming a frame rate of 24 fps, it will often require three or moreframe movements to completely traverse a one-inch wide detection zonefor motion detection to occur in a concurrent zone. Therefore, and inaccordance with another exemplary embodiment of the present invention,the prediction system retains the detection list even if no new motionis detected. When motion is detected in a new zone, that zone is addedto the detection list, conversely, when motion abates in a detectionzone, that zone is deleted from the list. Hence, the list is between 0and n entries long.

FIG. 10 is a flowchart of a method for accumulating a detectionsignature using a detection list in accordance with one exemplaryembodiment of the present invention. The process begins by receiving anew image frame (step 1002) and comparing the detection zones of thecurrent image frame with the corresponding detection zones in theprevious frame for changes in a manner discussed elsewhere above (step1004). If no motion is detected, two possible conditions may be present:the movement has left the area of the detection zones; or it hastemporarily subsided in the detection zones. If the movement has leftthe area of the detection zones, then the motion detected in the zoneswill abate sequentially. Consequently, the inactive zones are deletedfrom the detection list corresponding with the direction of movement.The only zone that might remain on the list may be an edge zone (eitherzone 1 or zone n). The list is checked for this condition (step 1006).If the detection list has only one entry, it can be deleted (step 1008),if not, the list is not altered and the next frame is processed (step1002).

The second condition occurs when a patient moves into some of thedetection zones and then stops moving. Incomplete traversals of thedetection zones are particularity problematic for reliable matching to adetection signature if the motion is not contiguous. In this situation,the detection list is retained at least initially, (even though thepatient is idle and no motion is detected in the current frame) and itreflects the previous state of patient movement. When the patientmovement resumes, the motion will be detected simultaneous in all zoneson the detection list and the fall predictions system continues to trackthe patient movement across the detection zones as described below. Forexample, assume a patient rolls partially off of the bed and comes torest without falling. As expected, motion is detected sequentially inzones 1 through n−1. Since no motion is detected in zone n, theprerequisite detection signature of a fall is not matched and the fallalarm is not issued. Nevertheless, the detection order is retained for apredetermined time period and the detection list is updated with any newchanges detected in the detections zones. The detection list cannot beretained indefinitely, and after some period of idle time it is assumedthat the movement has left the detection area and the detection list iscleared. This assumption may be false and the patient may simply beidle, but positioned across one or more detection zones. In order toaccount for this assumption, the fall prediction system correlates anymotion that is detected simultaneous in multiple zones with respect tothe most appropriate detection signature based on the most recent zonethat motion is detected. With continuing reference with the exampleabove, the detection list is cleared in response to the patient beingidle. When the patient continues, the fall prediction system will detectmovement in zones 1 through n−1 simultaneously, which does notconclusively match an inward movement or an outward movement detectionsignature. However, if new motion is then detected in zone n, the fallprediction system will recognize the detection signature as a fallsignature because the most recent motion detection is in the outermostzone with all other zones active.

In addition, the present fall prediction system discriminates patientmovements that are occasionally detected in the inner zones, zones 1 and2 and then subsides. Those detection signatures will not trigger a fallalarm unless motion is subsequently detected in all of the zones asdescribed immediately above. Furthermore, the present fall detectionmethodology distinguishes between non-contemporaneous motion detectedfrom both directions. For instance, patient movement detected in zone 1,zone 2, . . . , and zone (n−1) and later motion detected in zone n froman inward movement, which would seem to match a fall detectionsignature. However, without zone 1, zone 2, . . . , and zone (n−1) beingactive when the new motion in zone n is detected, it is assumed that themovement left the area of zones 1 through (n−1) prior to detecting thenew motion in zone n.

Returning to FIG. 10, if motion is detected in any one of the zones atstep 1004, a check is made to determine if motion is detected in a newzone, i.e., a previously inactive detection zone (step 1010). If not, acheck is made to determine if motion in a previously active zone hasabated (step 1012). If motion is not detected in a new zone (step 1010)and has not abates in a preciously active detection zone (i.e., themotion currently being detected is in the same zones as in the previousimage frame), the process reverts to step 1002 for a new image frame.If, on the other hand, motion has abated in a previously active zone(step 1012), that zone is removed from the detection list (step 1014).Typically, entries that are deleted will appear as the first or lastentry on the list. The process then reverts to step 1002 for a new imageframe.

Returning to step 1010, if the motion being detected is in a new zone,that zone is now active and is added as the last entry on the detectionlist (step 1016) and the detection signature is checked against knowndetection signatures for a match (step 1018). If the current list doesnot match any known signature (step 1020), the fall prediction systeminvokes an optional false alert routine to determine more precisely if afall alert should be issued at this time (step 1024) (the false alertanalysis is discussed below with regard to FIGS. 12A and 12B and thefalse alert routine is described below with regard to FIG. 13). Ineither case, a fall alert is issued (step 1026). Motion will becontinually detected in the zones even after a signature has beenmatched, which may result in multiple alerts being issued, or may beerroneously matched to other detections signatures by the fallprediction system. To avoid issuing multiple alerts from a single event,once a movement signature is matched, the fall prediction system invokesa clearing routine. The clearing routine (described below with regard toFIG. 11) delays any the issuance of any new alerts until all motionassociated with the current fall movement event subsides and prior tocontinuing the fall prediction process (step 1022). Conversely, if thedetection list does not match an outward signature (step 1020), butmatches an inward signature, the issuance of a fall alert in notwarranted. In that cased the clearing routine is immediately invokedprior to continuing the fall prediction process (step 1022).

The clearing routine is a mechanism that allows all motion associatedwith a fall movement match to subside prior to continuing the fallprediction routine. Hence, the routine is invoked immediately subsequentto a match. FIG. 11 is a flowchart of a method for clearing a detectionlist in accordance with one exemplary embodiment of the presentinvention. A frame count is started (step 1102) and the next framereceived (step 1104). The zones are analyzed for motion (step 1106), ifdetected the process restarts the frame counter (step 1102) andproceeds. If motion is not detected, the frame count is incremented(step 1108), and test for frame number n (step 1110). The aim here is toallow any residual noise in the image to die out prior to resuming thefall prediction routine. Depending on the frame speed, two to ten framesmay be checked for changes before resuming the fall prediction routine(i.e. 2<n<10) (step 1112). If motion is detected, the process reverts tostep 1102, restarts the frame counters and begins again. If no changesare detected within the zones over the n image frames, the detectionlist is cleared (step 1114) and the motion prediction routine resumed(step 1116).

As mentioned above, every patient bed fall is proceeded by an outwardmovement signature that traverses a set of detection zones although notevery outward movement signature is followed by a bed fall. Certainoutward patient movement from the origin are not precursors to a fall,such as the patient reaching of an object located on the night stand ortray. Therefore, some detection signature matches to outward movementare false alerts. FIGS. 12A and 12B are diagrams that illustrate thedistinctions between a patient movement that is a precursor to a falland a false alert. FIGS. 12A and 12B each illustrate a typical patientfall movement, wherein patient leg 1212 or patient arm 1214 sequentiallytraverses all of zones 1 through n (zones 1251, 1252, 1253 and 125 n),i.e., the detection list is (zone 1, zone 2, zone 3, . . . , zone n).While the movement of leg 1212 across the detection zones is a definiteprecursor to a fall, the movement of arm 1214 in not necessarily a fallmovement. Therefore, the movement depicted in FIG. 12B requires moreanalysis before issuing a fall alert, several methods are acceptable. Inthe first, the value for IDLE_RANGE is set high enough to discriminateany small changes in the intensity MOTION_Δ from a smaller object, suchas patient arm 1214. Alternatively, one or more of zones 1 through n maybe subdivided into k individual cells, cells 1261-126 k. Then,subsequent to matching a fall detection signature, the k cells arecompared with the k cells in the previous frame for changes. Changes inat least m cells would indicate that the detection signature is a fallsignature and not a false alert. The test is reiterated until the motionsubsides or a fall signature is indicated.

FIG. 13 is a flowchart of a method for discriminating a false alert froma fall alert in accordance with one exemplary embodiment of the presentinvention. At least one zone is subdivided into k cells and each of thek cells is compared with the h k cells of the previous image frame forchanges. Optimally, the process iterates through all n zones as depictedin the flowchart beginning with the closest zone to the origin, zone 1(step 1302). If motion is detected in m cells, a fall alert is issued(step 1304). If so the process ends. If not, the process continues tocheck zone 2 through n (steps 1306, 1308 and 1310) for changes in mcells, if detected a fall alert is issued (step 1304). If not, theprocess validates that motion was detected in at least one zone (step1312). The process retests the next image frame (step 1314) and iteratesback to step 1302. If no motion is detected in any zone, it is assumedthat the movement has left the area of the detection zones and theprocess ends.

The exemplary embodiments described below were selected and described inorder to best explain the principles of the invention and the practicalapplication, and to enable others of ordinary skill in the art tounderstand the invention for various embodiments with variousmodifications as are suited to the particular use contemplated. Theparticular embodiments described below are in no way intended to limitthe scope of the present invention as it may be practiced in a varietyof variations and environments without departing from the scope andintent of the invention. Thus, the present invention is not intended tobe limited to the embodiment shown, but is to be accorded the widestscope consistent with the principles and features described herein.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems which perform the specified functions or acts, or combinationsof special purpose hardware and computer instructions.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

What is claimed is:
 1. A method for predicting a condition of elevatedrisk of a fall comprising: receiving a surveillance viewport of an areafrom a surveillance camera; displaying the surveillance viewport on ascreen, the surveillance viewport showing a bed on the screen; receivinga user designation indicating a left risk line and a right risk line ofthe bed as displayed on the screen, the left risk line and the rightrisk line associated with an elevated risk of patient falls; creating aleft set of concurrent motion detection zones and a right set ofconcurrent motion detection zones, the zones of the left set created tobe separate from the zones of the right set, each of the left set andthe right set created to project laterally outward from the left riskline and the right risk line respectively, each of the left set and theright set respectively comprising at least an innermost zone and anoutermost zone, the innermost zone of the left set extending along andadjacent to the left risk line, the innermost zone of the left setpositioned between the left risk line and the outermost zone of the leftset, the innermost zone of the right set extending along and adjacent tothe right risk line, the innermost zone of the right set positionedbetween the right risk line and the outermost zone of the right set,each of the left set and the right set being automatically created by acomputing system based on the user designation indicating the left riskline and the right risk line, wherein each of the left set and the rightset respectively comprise at least one detection zone between theinnermost detection zone and the outermost detection zone; monitoringfor motion in each zone of each of the left set and the right set basedon a plurality of frames sequentially generated by the surveillancecamera while viewing the bed; detecting a plurality of movementsignatures of movement traversing one or both of the left set and theright set, the plurality of movement signature comprising an outwardmovement signature associated with high patient fall risk from the bedand an inward movement signature that is not associated with highpatient fall risk from the bed, wherein the outward movement signatureis detected based on motion being first detected within the innermostzone of either of the left set or the right set before motion isdetected in any other zones of the left set or the right set, andwherein the inward movement signature is detected based on motion beingfirst detected within the outermost zone of either of the left set orthe right set before motion is detected in any other zones of the leftset or the right set, the plurality of movement signatures detected bythe computing system; and issuing a fall alert with the computing systembased on the detection of the outward movement signature.
 2. The methodof claim 1, wherein the user designation is received from a user inputdevice.
 3. The method of claim 1, wherein the user designation comprisesplacement of a bounding box over the bed as displayed on the screen. 4.The method of claim 3, wherein the user designation comprisesmanipulation of the bounding box as displayed on the screen tocorrespond to the orientation of a bed.
 5. The method of claim 1,wherein the user designation indicates risk lines which extend alonglateral sides of the bed.
 6. The method of claim 1, wherein theinnermost zone of the left set is coextensive with the left risk lineand the innermost zone of the right set is coextensive with the rightrisk line.
 7. The method of claim 1, wherein the left risk line and theright risk line correspond to virtual bedrails of the bed.
 8. The methodof claim 1, wherein monitoring for motion comprises comparing grayscaleor RGB values of the pixels of each zone with grayscale or RGB values ofthe corresponding zone of a previous frame and calculating a changevalue.
 9. The method of claim 1, wherein the outward movement signatureis detected from a chronological order of motion detections that beginwith motion in the innermost detection zone of one of the left set orthe right set and ends with motion in the outermost detection zone ofthe left set or the right set.
 10. The method of claim 9, wherein theinward movement signature is detected from a chronological order ofmotion detections that begin with motion in the outermost detection zoneof one of the left set or the right set and ends with motion in theinnermost detection zone of the left set or the right set.
 11. Themethod of claim 1, wherein the outward detection signature is detectedacross either of the left set or the right set based on motion beingfirst detected within the innermost detection zone and then beingsequentially detected across the at least one detection zone and thenbeing detected within the outermost detection zone.
 12. The method ofclaim 11, wherein the inward detection signature is detected acrosseither of the left set or the right set based on motion being firstdetected within the outermost detection zone and then being sequentiallydetected across the at least one detection zone and then being detectedwithin the innermost detection zone.
 13. A surveillance system fordetecting an elevated fall risk condition, the system comprising: asurveillance camera configured to generate a plurality of frames showinga surveillance viewport of an area including a bed; a user interface,the user interface comprising a user input and a display, the displayconfigured to display the surveillance viewport showing the bed, theuser input configured to generate a user designation indicating a leftrisk line and a right risk line of the bed as displayed on the display,the left risk line and right risk line associated with an elevated riskof patient falls; and a computer comprising memory and logic circuitryconfigured to: receive the user designation indicating the left riskline and the right risk line of the bed; create a left set of concurrentmotion detection zones and a right set of concurrent motion detectionzones based on the user designation indicating the left risk line andthe right risk line of the bed, the zones of the left set created to beseparate from the zones of the right set, each of the left set and theright set created to project laterally outward from the left risk lineand the right risk line respectively, each of the left set and the rightset respectively comprising at least an innermost zone and an outermostzone, the innermost zone of the left set extending along and adjacent tothe left risk line, the innermost zone of the left set positionedbetween the left risk line and the outermost zone of the left set, theinnermost zone of the right set extending along and adjacent to theright risk line, the innermost zone of the right set positioned betweenthe right risk line and the outermost zone of the right set, whereineach of the left set and the right set respectively comprise at leastone detection zone between the innermost detection zone and theoutermost detection zone; monitor for motion in each zone of each of theleft set and the right set based on the plurality of frames; detect aplurality of movement signatures of movement traversing one or both ofthe left set and the right set based on the monitoring for motion, theplurality of movement signatures comprising an outward movementsignature associated with high patient fall risk from the bed and aninward movement signature that is not associated with high patient fallrisk from the bed, wherein the outward movement signature is detectedbased on motion being detected within the innermost zone of either ofthe left set or the right set before motion is detected in any otherzones of the left set or the right set, and wherein the inward movementsignature is detected based on motion being detected within theoutermost zone of either of the left set or the right set before motionis detected in any other zones of the left set or the right set; andissue a fall alert with the user interface based on the detection of theoutward movement signature.
 14. The system of claim 13, wherein the userdesignation comprises placement of a bounding box on the bed asdisplayed on the display.
 15. The system of claim 14, wherein the userdesignation further comprises manipulation of the bounding box on thesurveillance viewport to correspond to the orientation of the bed. 16.The system of claim 13, wherein the user designation indicates risklines which extend along the lateral sides of the bed.
 17. The system ofclaim 13, wherein the computer is configured to create the innermostzone of the left set coextensive with the left risk line and theinnermost zone of the right set coextensive with the right risk line.18. The system of claim 13, wherein the left risk line and the rightrisk line correspond to virtual bedrails of the bed.
 19. The system ofclaim 13, wherein the computer is configured to monitor for motion bycomparing grayscale or RGB values of the pixels of each zone withgrayscale or RGB values of the corresponding zone of a previous frame ofthe plurality of frames and calculate a change value.
 20. The system ofclaim 13, wherein the computer is configured to detect the outwardmovement signature based on a chronological order of motion detectionsthat begin with motion in the innermost detection zone of one of theleft set or the right set and ends with motion in the outermostdetection zone of the left set or the right set.
 21. The system of claim20, wherein the computer is configured to detect the inward movementsignature based on a chronological order of motion detections that beginwith motion in the outermost detection zone of one of the left set orthe right set and ends with motion in the innermost detection zone ofthe left set or the right set.
 22. The system of claim 13, wherein thecomputer is configured to detect the outward detection signature withineither of the left set or the right set based on motion being firstdetected within the innermost detection zone and then being sequentiallydetected across the at least one detection zone and then being detectedwithin the outermost detection zone.
 23. The system of claim 22, whereinthe computer is configured to detect the inward detection signaturewithin either of the left set or the right set based on motion beingfirst detected within the outermost detection zone and then beingsequentially detected across the at least one detection zone and thenbeing detected within the innermost detection zone.